So, check engine light comes on -- OBD II says it's a fault in #3 cylinder -- I notice that car generally runs fine w/o symptoms, EXCEPT, for first start-up of the day, when it misses and sputters a bit until it smooths out. Thereafter, it runs fine, until it sits overnight and it starts roughly the next day. I replace all spark plugs and, for good measure, the ignition coil for #3. No difference -- rough start in morning, smooth rest of day, check engine light stays on. So now what? It would appear that something - gas? oil? - is seeping into the cylinder when car sits for a long period. No oil smell, though, or blue smoke when car starts. Any ideas?